Treated lubricant



.Patentea Sept. '27, 1938 UNITED STATES 2,131,}38 TREATED LUBRICANT Albert Ernst Ganzert, Chicago, IlL, assignor to Ernest 0. Shaw No Drawing. Application December 11,1935,

' Serial No.53,999 i l This invention relates toa treated lubricant, and to a method of treatment for improving the qualities of lubricants subjected thereto.

One object of this invention is to produce a 5 finished lubricant which will form a. highly persistent and tenacious lubricating film on a surface: another object is to produce a film forming lubricant whose film remains substantially intact when exposed to the action of water, water 10 vapor, the wiping action of rolling or sliding parts, the scrubbing action 'of foreign material, the displacing action of heat and load, and the dissolving action of solvents derived from hydrocarbons, such as gasoline, kerosene, etc. Yet an- ]5 other object of this invention is to provide a fin-- ished lubricant having a high degree of oiliness and penetration and resulting in a lower coefficient of friction between surfaces, while at the same time forming afilm which persistently adheres to such surfaces; other and further objects and advantages will appear in the specifications following.

I have found that bytreating an ordinary refined hydrocarbon lubricant with fatty acid salts 25 of polyvalent bases, particularly of aluminum, and mono or dibasic oxides and their like fatty acid salts, as zinc forv example, in proper proportions, 2. change is produced in the lubricant giving it the qualities or characteristics men 0 tioned above, along with other desirable qualities.

I have found that, generally speaking, the higher the molecular weight of the fluid or substance being used as a lubricant the lower the coefiicient of friction between two surfaces sepa- 5 rated by a film of such substances. For example, the coeflicient of friction between two pieces of polished hard steel having a film of hydrocarbon lubricant; knowrrg-as undecane between them, which particular lubricant has a molecular weight 40 of 156, is .517. Where a liydrocarbon lubricant having a. higher molecular weight isused, such as tetracosane having a molecular'weight of 338, the value of the coemcient of friction between the steel surfaces is reducedto .165. Assuming 45 the lubricants to be composed of saturated hydrocarbons, it can be seen that the reduction in the coefiicient for each CH2 group added is considerable, the reduction from undecane (about the lowest molecular weight suitable for general 50 lubricants) to tetracosane being about 68%. The difliculty with the saturated hydrocarbons of higher molecular weight, however, is that they produce a fluid which is unsuitable for ordinary lubricant use, since it is eitlier exceedingly-vis- 55 cous or even solid at normal temperatures.

brication properties which result in low c'oeffi- 'cients of friction between adjacent metal surfaces. Stearic acid, for example, having a molecular weight of 284 produces a coeflicient of friction under the above conditions of .0052.

It is clearly deducible from these results that if still larger molecules could be used and could be kept in a fluid state at low temperatures, great benefit would accrue to the lubricants from their presence. In order to obtain the benefit of such higher molecular values I have made use of fatty acid salts of polyvalent bases in the usual refined hydrocarbon lubricant. As an instance of my invention, 1 will take as a specific example,

aluminum stearate having .a'mol'ecular weight of 877, which is three and one-half times that of octadecane, the highestmolecular weight saturated hydrocarbon which remains liquid'at nor mal temperatures. I have found, however, that even when small quantities of aluminum stearate are dissolved in a hydrocarbon lubricant it 1 adds to the oilexcessive and undesirable viscosity. Such a. product,.without further treatment, is impractical fonordinary lubrication purposes, as in an automobile engine.

I have found that the addition to such a product, of reagents of a precipitating character, such as zinc oxide along with a like-fatty acid salt of the same base (zinc stearate in'this case) in certain definite proportions, results in a. reduction of the viscosity of a plain solution of aluminum 40 stearate, substantially lowering the viscoslty of this flnal mixture below that of the plain untreated hydrocarbonlubricant in the cold and maintaining a slightly higher viscosity at elevated temperatures. It is necessary to'add these. reagents in quantities just short of the precipitatingamounts, so that the resulting compound takes on the character of a colloid or colloidal suspension wherein the heavier molecules are dispersed throughout the hydrocarbon medium and remain suspended therein. I

The following is given as an example -to illus-' trate the chan es in viscosity produced by-the 1 addition of the zinc salts.' Acommercial straight-- mineral oil having a 8.5.. E. viscosity rating'of I 40 was used as a base, and in it was dissolved by heating, at about 200 F., 1,782% by weight of aluminum stearate, a monobasic fatty acid salt of aluminum. A mixture of zinc stearate and zinc oxide was then made up, the compound containing approximately 15% zinc oxide. This compound was then added to another similar solution (S. A. E. 40 mineral oil and 1.782% aluminum stearate) in just sufllcient quantities so that no fioc was .formed when the resulting compound wasdissolved in a light benzine. For comparison, the two treated lubricants will be called Nos. 1 and 2, No. 1 being the hydrocarbon and 1.782% aluminum stearate, No. 2 being the same as No. 1 plus the zinc salts. The Saybolt viscosities gave the following results:

No. 1 No. 2

- Saybolt Saybolt Temperature Seconds Temperature Seconds Degrees F. Degrees F 240 252 240 56 210 390 210 74 130 130 .368 100 889 Impossible to take.

Not'only does the lubricant No. 1' have more than five times the viscosity at 210 F., as does lubricant No. 2, but lubricant No. 2 also shows greater resistance to displacement by heat, water,

water vapor, pressure, the wiping action of rolling or sliding parts and the scrubbing action of foreign materials but also shows a lower coeflicient of friction, From .5 to 167% of the compound as in No. 2 above is sufiicient to give very beneficial results to the untreated oil:

, Although zinc oxide is a precipitant for aluminum salts, the reaction between zinc oxide and aluminum stearate or other monobasic fatty acid salt of aluminum is such that it requiresthree molecules of zinc oxide to precipitate two molecules of aluminum stearate. In the making of the compound, above identified as No. 2, approximately five molecules of the aluminum salt to one'molecule of zinc oxide was used. Slight or partial precipitation from a molecular solution,

as here, forms aggregates within the colloidal size.

small changesfrom the critical proportions will cause flocculation and subsequent precipitation.

It is believed that the: above proportions of zinc salts andaluminum stearate are just .sufiicient to cause a. rearrangement of the electron systems withinthe molecule, thus developing an electrical. charge om each particle which repels other like particles'and enables them to main- 65 tain a separate existence. This same charged particle, moreover, is attracted to, and firmly held upon, any surface exhibiting an opposite adsorbed filmwill be instantly replaced so long as properly charged particles remain in the lubricant medium flowing across the metal surface.

Whether or not this be the true explanation,

however, it is a fact that oil treated, as disclosed herein forms a film of'adsorbed molecules on the metal surface of a-bearing or the like, which film clings much more tenaciously than is the usual case and repairs itself more quickly if ruptured ering again this adsorbed film, it is clear that the larger the size or volume of the molecules of which it is construed, the greater the distance between the rubbing surfaces will be, and, if this adsorbed film is composed of substances that will resist the compressive eifect of pressures or load to a greater degree than ordinary hydrocarbon,

' the film will continue to function under conditions that would otherwise cause failure.

-In order to increase the adsorbing ability of the lubricant film and thus to add to the load carrying ability of the above-mentioned lubricant, it has been found advantageous to add a small percentage of some chlorine derivative of the hydrocarbons, especially the lower hydrocarbons. These chlorine derivatives are prefera-bly of the class in which all of the hydrogen atoms. are replaced by chlorine atoms, as for instance carbon tetrachloride. For example, a

straight parafifin oilhaving an S. A. E. viscosity of 30 was used for a test, and to onesample thereof one per cent of the above-mentioned aluminum zinc compound was added and a little 'over 3% of carbon tetrachloride. The straight 0il, tested on a,filrn strength testing machine, seized at 7,500 pounds per square inch. The

' treated sample of the same oil was run on the same machine to 73,500 pounds per square inch,

which was the limit of the capacity of the ma-,

chine, and no seizure occurred. In addition,

such treated oil suffers much less change in color under heating in an oven for twelve hours at 350 F., and shows no corrosive efiects, whatsoever, on pieces of metal and bearing alloys immersed, in the oil for nine hours at about 300 F.

For illustrative purposes in the foregoing example, carbon tetrachloride was mentioned. In

practice all of the halogen derivatives of the lower hydrocarbons seemed to be advantageous,

tetrachloride would be used on account of its relatively low cost since carbon tetrachloride has a boiling point around 170 F. However, carbon dichloride. would be used where the oil temperature of the bearing surfaces would be around '200" F., for example, Where both load and com- (having an atomic weight of 79.92 as against that of chlorine, 35.46) may be substituted roichlorine where it' is desired to operate under higher temperatures. i

Thefforegoing detailed description given for clearness of understanding only, and

no unnecessary limitations should be understood therefrom, but the appendedclaims should be construed as broadly as permissible, in view of the prior art.

adapted to be used as a liquid lubricant: from,

three-tenths to flve per cent of aiuminum stearate;. and less than one-twenty-fii'th as much zinc oxide and less than one-fifth as much zinc stearate.

2. A lubricant ofsthe character described, liquid at ordinary temperatures, having a low coemcient of friction and adapted to form a persistent film stable under high pressures and tem- 'peratures including: a hydrocarbon oil; a small proportion of aluminum stearate; a quantity of a mixture of zinc stearate and zinc oxide large enough to cause colloidal suspension of the compounds of metals present in said lubricant and small enough that precipitation of said compounds will not occur.

3. A lubricant oi the character described, liquid at ordinary temperatures, having a low coeilicient of friction and adapted to form a persistent mm stable under high pressures and temperatures including: a hydrocarbon oil; approximately 25% of aluminum stearate; approximately 0.1% of zinc oxide; andapproximately 0.6% of zinc stearate. p v

4. A lubricant of the character described in claim ,1 including less than 5% of carbon tetrachloride.

ALBERT ERNST GANZERT. 20 

